• Parasites, Hosts and Diseases
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• v.31 no.1
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• pp.7-12
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• 1993

Metaceriae of Parvatrema timondavidi (Digenea; Grmnophallidae) were found from Tapes phillippinarum, one of the most common marine clams in Korean. T. were philippinarum was collected from a fishery market in seoul, and all of the clams eximined were found to contain many gymnophyallid metacercariae. To get adult worms, 10 ICR mice were fed with 100 metacercariae each and sacrificed by cervical dislocation at 7, 10 and 14 mice were morphologically characterized by oval body shape, lage oral sucker with lateral located genital pore from the venttral sucker. Based on these characters they identified as P.timondawvidi Bartoli, 1964. this study first confirms the presence of P. timondawcidi metacercartae in T.philippinarum in Korea.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.693-701
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• 2012

In this study, a small wind turbine airfoil specialized for national wind condition was designed in order to develop the furling control type HAWT. And then a flow analysis was carried out based on the blade drawing which was designed to characterize of the developed airfoil. The result of the flow analysis showed that the torque on the 3 blades was 180.23N.m. This is equivalent to an output power of 5.66kw and an output efficiency of 0.44. Then we produced and constructed a 3kW - furling control type HAWT by getting the system unit design technology such as the specialized furling control device. By operating this turbine, we could get 3kW of the rated power at a wind speed of 10.5m/s through the ability test. Cut-in wind speed was 2m/s, generator efficiency was 92% at the rated power output. Sound power level was 87.2dB(A). Also we observed that the output power was limited to 10.5m/s with furling system operation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.487-495
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• 2012

The yaw control, a major part of the wind turbine, is closely related to the efficiency of electric power production and the mechanical load. The yaw error, which results from the nacelle not being appropriately aligned in the wind direction, not only decreases the power output but also reduces the lifetime of the wind turbine as a result of large fatigue loads. However, the yawing rate cannot be increased indefinitely because of constraints on mechanical loads. This paper investigates the characteristics of an active yaw control system, the basic principle of the system, and mechanical loads around the yaw axis during yawing.

• Journal of the Korean Solar Energy Society
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• v.32 no.4
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• pp.1-8
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• 2012

A Fiber Bragg Grating (FBG) sensor imbedded small wind turbine blade was manufactured to experimentally investigate the feasibility to embed FBG sensors between layers of glass fiber to monitor dynamic strains of the wind turbine blade. The blade which is similar to a commercial 300 W wind turbine blade was manufactured with glass fiber as a reinforcement and epoxy resin as base material. A total of five FBG sensors including one temperature sensor were imbedded in the blade to sense mechanical strain and temperature. While manufacturing the blade, residual strain and temperature that occurred in the small wind turbine blade were monitored using the imbedded FBG sensor array. To examine the sensor performance, an impact test was carried out. The experimental results from the FBG sensors were close to those from electrical strain gages mounted on the blade root surface. The mode shapes of the blade were analyzed also using a commercial Ansys simulation with a model obtained from a three dimensional laser scanning of the blade.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.681-688
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• 2000

In this paper, a planar antenna that is small and light, is designed and analyzed aiming handset antenna of IMT-2000. Employing the Ensemble simulator based on a MoM, design-parameters are found to determine a resonant frequency. Therefore, it is analyzed with the Ensemble simulation and FDTD numerical for resonating at the allocated frequency for IMT-2000 in the fixed antenna dimension of 21$^{\circ}$wing angle that is a design parameter. Analyzing with FDTD method, Though the results of FDTD are very exact, this analysis introduces errors due to the staircasing approximation in the slope of bowtie. To reduce this error, it is divided to 4-ranges where the cell contains the boundary of perfect conductor/free space. Then, each range is calculated by different by different equation, which modify the H-field to add the component of the area and length of the cell filled with free space. Therefore, the modified FDTD algorithm provided with a narrow bandwidth of return loss calculated with a standard FDTD algorithm that can be extended to the desired ranges.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1672-1677
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• 2004

Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modem air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras($1280pixel{\times}1024pixel$) were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

• Korean Journal of Construction Engineering and Management
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• v.9 no.3
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• pp.118-125
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• 2008

In Korea, five days per week system, duration reduction bidding system, and post sale system have recently stimulated an interest in productivity improvement in construction project. However, analysis result of productivity in Korean construction industry found that the productivity is too low. APC (Architectural PC) is alternative of reveal wall and parapet in apartment housing prcjects and is used abroad broadly because of duration reduction for productivity improving. APC is used as external curtain wall in Dubai, North America, and Southeast Asia. Therefore, it is proposed that necessary to Introduce APC in Korea. The objective of this study is to draw up introduction of APC in apartment housing projects. We analysed the feasibility of the use of APC. The survey results reported that APC would be able to improve the productivity in the eight productivity factors.

• Journal of the Korean GEO-environmental Society
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• v.20 no.8
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• pp.13-20
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• 2019

In order to ground reinforcement, the chemical grouting, the anchor, the soil nailing system, the micropile, etc. can be mentioned by the methods widely used in domestic. The above ground reinforcement methods are developed by various methods depending on the type of reinforcement, installation method, presence of prestress, grouting method, etc. However, in common, the strength of reinforcement, the friction force of grout and reinforcement and the friction force of grout and ground are the main design variables. Therefore, the optimized ground reinforcement is a material with a high tensile strength of the reinforcement itself, the friction force between the reinforcement and the grout is high, and the application of an optimal grouting method is necessary to improve the friction force between the grout and the ground. In this study, a total of 20 model tests were conducted to analyze the reinforcement effects according to the shape of the reinforcement and the grouting method. As a result of the test, As a result of the experiment, it is judged that the reinforcing effect is superior to the perforated + wing type reinforcement and post grouting method.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.65-80
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• 2019

With the advent of the ICT-based 4th industrial revolution, the convergence of the manufacturing industry and ICT seems to be the new breakthrough for achieving the company's competitiveness and play a role on the key element for accelerating the revival of the manufacturing industry. When the smart factory is implemented, each plant can analyze the quantity of data collected, build the data-driven operation systems which can make decisions, and ultimately discover the correlation among many events in the manufacturing sites. As the customers' needs become diversified more and more, it is required for the company to change its operating method from large quantity batch production systems to customizable and flexible manufacturing systems. For performing this requirements, it is essential for the company to adopt the smart factory. Based on technology acceptance model (TAM), this study investigates the factors influencing continuous use intention and switching intention of the smart factory. To do so, a questionnaire survey is conducted both online and offline. 122 samples are used for the study analysis. The results of this study will provide many implications with many researchers and practitioners relevant smart factories.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.10
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• pp.677-690
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• 2022

By using an actuator disk method based flow solver, aerodynamic analysis is carried out for a dual ducted fan aircraft, which is one of the VTOL compound aircrafts, and its associated ground effect is analyzed. The characteristics and accuracy of the solver for ground effect analysis is evaluated through a comparison with the results obtained from the sliding mesh technique. The aerodynamic performance and flow field characteristics with respect to the distance from the ground are analyzed. As the ground distance decreases, the fan thrust increases, but the deterioration of total normal force and hovering flight efficiency is identified owing to the decrease in the vertical force of the duct, fuselage, and wing. By examining the flow field in the bottom of the fuselage, the ground vortices and fountain flow generated by the interaction of the fan wake and ground are identified, and their influence on the aerodynamic performance is analyzed. The strength and characteristics of outwash with respect to the ground distance and azimuth direction are analyzed through comparison/examination of velocity profile. Influence of the ground effect with respect to collective pitch angle is also identified.